The present invention relates to a database processing technique used in operation of a database.
The online business performing the conventional large amount of transaction processing requires daily, weekly, and monthly processing such as a large amount data calculation and batch registration or a periodical batch processing such as database backup and re-organization. Since these processes are accompanied by batch access of a database used by the online service, the online business is greatly affected by it and it disturbs provision of 24-hour continuous service (function realized by execution of a program and an object).
Recently, the SAN (Storage Area Network) configuration organically connecting a plurality of storage devices such as magnetic disc devices by a dedicated high-speed network is in widespread use. In this configuration, the storage device provides a function of high-speed copying of an arbitrary logical volume to a plurality of logical volumes, a function of data multiple writing by making an arbitrary logical volume a main volume and the other plurality of logical volumes sub-volumes, a function of disconnecting the logical volume in the multiple write mode at an arbitrary moment and accessing the main volume and the sub-volumes independently of each other, and a difference reflection function for making an arbitrary volume a main volume and another logical volume a sub-volume and resuming the multiple write so that only a difference between the data is reflected from the main volume to the sub-volume.
Moreover, a duplicate database access device has been suggested in US Patent Application Publication number US 2002/0198899A1. When one of the database areas multiple-written or duplicated by the external storage device is disconnected and a physical duplicate database is created, it is possible to maintain consistency of the duplicate database while continuing the transaction processing and to access a plurality of physical databases without modifying the application program which has been accessing the duplicate origin database.